USB Transfer Speeds
Data transfer rates quoted for USB2.0 hard drives and other USB peripherals usually state 480Mbps (Mega bits per seconds) which is 57MB/second (Megabytes per second). However, it is impossible to achieve this rate of transfer.
Computer Processing Power
In the real world, there are many factors that limit the lofty claims of 480Mbps.The primary reason why USB2.0 cannot achieve its stated claims it that the USB bus uses a lot of computer processing power to transfer data. Secondly, if you have a fast external data storage device, like an external hard disk and are copying data from a laptop, the hard disk of the laptop will not be able to keep up with the required data output. When copying from the external hard drive to the computer, the same will apply.
Transferring Data Files
Thirdly, the size of the data file will affect the data transfer. Copying one large file is actually faster than lots of small files, as the computer's processor needs to open, copy and close each file it is copying. A fourth factor that may affect the transfer speed is when two USB devices are on the same bus and therefore the available bandwidth.
What then can be expected in terms of USB2.0 data transfer? Depending on the computer and the external hard drive you attach to the computer, you should be able to get anywhere from 10MB-30MB/per second which is still very fast.
Peer To Peer Data Transfer
FireWire will actually transfer data faster than USB2.0 when using the same equipment and claims data transfer rates of 400Mbps. The faster transfer rate is due to the fact that FireWire uses what is called a 'peer to peer' type of data transfer. Peer to peer enables the FireWire bus to do the data transfer, rather than getting the computers processor involved. This means less traffic inside the computer and therefore faster data transfer.
Should you upgrade to FireWire? Although lower than what is claimed, the massive data transfer rates that USB2.0 can achieve will suffice for most applications. Only if you want to squeeze every last drop of performance from your computer and peripheral should you consider upgrading.